Astronomers using the Hubble Space Telescope are at the dawn of a
new era in exploring the universe. With two powerful new
instruments, added to Hubble in February 1997 by the crew of the
Space Shuttle Discovery, we can literally peer light years beyond
what was possible before.

Our deepest look into space so far is the 10-day exposure by this
telescope, called the Hubble Deep Field, that is
celebrated in the first of the three "Mysteries of Deep Space"
programs. That image is believed to reveal galaxies back to
about 10 per cent of the present age of the universe, meaning to
within about a billion years after the Big Bang. But now we can
look further back still; back in time and far out in space.
Light from the very distant and ancient galaxies is shifted
towards very long wavelengths by the famous red shift of the
expanding universe, as explored by Edwin P. Hubble himself.
Light that was blue or yellow when it left the distant galaxies
has been shifted to the invisible infrared region of the spectrum
by the time it nears the Earth. This makes the Hubble Space
Telescope's new Near Infrared Camera and Multi-Object
Spectrometer - the ideal instrument
to receive it. With NICMOS, it should be possible to peer into
the Hubble Deep Field to the distance where galaxies (if such
exist that far back) are seen when the universe had attained only
five percent of its present age.

A second new instrument on the Hubble Space Telescope will
multiply its scientific output. Until recently, each of the two
original spectrographs on board (both of them removed from the
Telescope in February by the Discovery crew) could record the
spectrum of only one star at a time, or the spectrum of only one
location in a galaxy or nebula at a time. Yet it is spectra
which are the astronomer's most powerful diagnostic tool: from
them we learn the chemical composition, temperature, density,
pressure, and other properties of celestial objects. With the
new Space Telescope Imaging Spectrograph the spectra of as many
as 500 adjacent locations on the sky can be observed
simultaneously. This huge so called multiplex advantage will
enable projects that were impractical before. This is especially
important in the hunt for giant black holes near the centers of
galaxies. Previously, Hubble Telescope users had to make
multiple successive observations of the spectra at different
locations around a galaxy center in order to determine the rate
at which the stars and gas are orbiting the center. The more
powerful the source of gravity, the faster they whirl. Where
speeds are high enough, the presence of a very massive black hole
is deduced.

Now, a systematic census of galactic centers is
possible with STIS, so that the Hubble Telescope can tell us
whether giant black holes are standard features of normal
galaxies, or rare oddball components of the universe. With its
more sensitive detectors, the STIS will also permit spectroscopic
analysis on more distant objects than previously possible with
the Hubble Telescope.

In a year or two's time, the Telescope may complete a second
Hubble Deep Field, this time in the southern sky, for comparison
with the existing observation, which looked far to the north.
In 1999, a new Advanced Camera for Surveys will be added to the
Telescope's instrument complement. This camera will enable us to
photograph a larger area of the sky at one time than Hubble could
do before, and its images will be even sharper than those we now
obtain. Beyond the new Millennium, an additional instrument to
make Hubble's explorations more rewarding yet is to be added in
the year 2002. Scientists at many laboratories are submitting
proposals to NASA this month for the possible forms that the 2002
instrument might take. By current plans, the mission of the
Hubble Space Telescope will end in 2005, but astronomers
everywhere are hoping that it may continue even longer into the
21st Century. Some day, a Next Generation Space Telescope, now in the study phase, may
become a reality. It would dwarf the Hubble Space Telescope and
represent a quantum leap in capability to explore the most remote
regions of the universe.